SMOKE NUISANCE. Smoke is produced the incomplete combustion of fuel, tiny bits of uncensumed matter being wafted into the air by the gases which are liberated and not decomposed. In order to effect complete combustion, it is nec essary that all the constituent gases be raised to a very high temperature and mixed with oxygen before the temperature falls.
The difference betweeeu bituminous and anthra cite coal is that while anthracite is composed of almost pure carbon, bituminous contains in ad dition to the fixed carbon a compound of carbon and hydrogen, which makes, under present meth ods, all the trouble. When bituminous coal is ignited these hydrocarbons are first volatilized by the heat, then the hydrogen unites with the oxygen of the air and the carbon is it free. These free carbon particles are made incandes cent by the intense heat, and it is this which produces the bright flame so characteristic of bituminous coal. if there is at this stage a sufficient supply of oxygen and enough, but not too much, heat, the carbon will he transformed into carbonic acid gas and combustion will be complete. If there is not enough oxygen some of the free particles of carbon will escape through the chimney as smoke. Smoke will also be pro duced by the 'volatilization of the hydrocarbons at a heat, less than that necessary to separate the hydrogen from the carbon; or if, on the other hand, the heat is so suddenly intense that some of the fixed carbon is carried off before it has time for combustion. All the conditions neces
sary for complete or smokeless combustion may be met by properly constructed furnaces and in telligent firemen.
In recent years a number of American States have authorized some or all cities within their boundaries to prohibit the emission of dense smoke from chimneys and smoke-stacks and to establish special departments to abate the smoke nuisance. In 1903 such departments existed in Chicago, Saint Louis, and Cleveland. In New York the local Board of Health has authority in this matter. The smoke nuisance has also been the subject of general legislation in foreign coun tries, notably in Great Britain.
BIBLIOGRAPHY. Littlejohn, article "Effects of Bibliography. Littlejohn, article "Effects of Smoke and Fog on Health," in the Sanitary Rec ord (June 18, 1897; also November 4, 1898) ; Journal of time Franklin Institute (Philadelphia, 1897-9S, and 1S98) containing the reports made to the committee appointed to investigate the subject of smoke prevention by various special ists :• "Coal Combustion and Smoke Prevention," in .1 meriran Gas-Light Journal, August 29, 1898.